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Journal ArticleDOI

Carbon-based materials as supercapacitor electrodes

19 Aug 2009-Chemical Society Reviews (The Royal Society of Chemistry)-Vol. 38, Iss: 9, pp 2520-2531
TL;DR: This tutorial review provides a brief summary of recent research progress on carbon-based electrode materials forsupercapacitors, as well as the importance of electrolytes in the development of supercapacitor technology.
Abstract: This tutorial review provides a brief summary of recent research progress on carbon-based electrode materials for supercapacitors, as well as the importance of electrolytes in the development of supercapacitor technology. The basic principles of supercapacitors, the characteristics and performances of various nanostructured carbon-based electrode materials are discussed. Aqueous and non-aqueous electrolyte solutions used in supercapacitors are compared. The trend on future development of high-power and high-energy supercapacitors is analyzed.
Citations
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Journal ArticleDOI
TL;DR: Two important future research directions are indicated and summarized, based on results published in the literature: the development of composite and nanostructured ES materials to overcome the major challenge posed by the low energy density.
Abstract: In this critical review, metal oxides-based materials for electrochemical supercapacitor (ES) electrodes are reviewed in detail together with a brief review of carbon materials and conducting polymers. Their advantages, disadvantages, and performance in ES electrodes are discussed through extensive analysis of the literature, and new trends in material development are also reviewed. Two important future research directions are indicated and summarized, based on results published in the literature: the development of composite and nanostructured ES materials to overcome the major challenge posed by the low energy density of ES (476 references).

7,642 citations

Journal ArticleDOI
24 Jun 2011-Science
TL;DR: This work synthesized a porous carbon with a Brunauer-Emmett-Teller surface area, a high electrical conductivity, and a low oxygen and hydrogen content that has high values of gravimetric capacitance and energy density with organic and ionic liquid electrolytes.
Abstract: Supercapacitors, also called ultracapacitors or electrochemical capacitors, store electrical charge on high-surface-area conducting materials. Their widespread use is limited by their low energy storage density and relatively high effective series resistance. Using chemical activation of exfoliated graphite oxide, we synthesized a porous carbon with a Brunauer-Emmett-Teller surface area of up to 3100 square meters per gram, a high electrical conductivity, and a low oxygen and hydrogen content. This sp 2 -bonded carbon has a continuous three-dimensional network of highly curved, atom-thick walls that form primarily 0.6- to 5-nanometer-width pores. Two-electrode supercapacitor cells constructed with this carbon yielded high values of gravimetric capacitance and energy density with organic and ionic liquid electrolytes. The processes used to make this carbon are readily scalable to industrial levels.

5,486 citations

Journal ArticleDOI
TL;DR: In this article, the pseudocapacitance properties of transition metal oxides have been investigated and a review of the most relevant pseudo-capacitive materials in aqueous and non-aqueous electrolytes is presented.
Abstract: Electrochemical energy storage technology is based on devices capable of exhibiting high energy density (batteries) or high power density (electrochemical capacitors). There is a growing need, for current and near-future applications, where both high energy and high power densities are required in the same material. Pseudocapacitance, a faradaic process involving surface or near surface redox reactions, offers a means of achieving high energy density at high charge–discharge rates. Here, we focus on the pseudocapacitive properties of transition metal oxides. First, we introduce pseudocapacitance and describe its electrochemical features. Then, we review the most relevant pseudocapacitive materials in aqueous and non-aqueous electrolytes. The major challenges for pseudocapacitive materials along with a future outlook are detailed at the end.

3,930 citations

Journal ArticleDOI
TL;DR: The unique advances on ultrathin 2D nanomaterials are introduced, followed by the description of their composition and crystal structures, and the assortments of their synthetic methods are summarized.
Abstract: Since the discovery of mechanically exfoliated graphene in 2004, research on ultrathin two-dimensional (2D) nanomaterials has grown exponentially in the fields of condensed matter physics, material science, chemistry, and nanotechnology. Highlighting their compelling physical, chemical, electronic, and optical properties, as well as their various potential applications, in this Review, we summarize the state-of-art progress on the ultrathin 2D nanomaterials with a particular emphasis on their recent advances. First, we introduce the unique advances on ultrathin 2D nanomaterials, followed by the description of their composition and crystal structures. The assortments of their synthetic methods are then summarized, including insights on their advantages and limitations, alongside some recommendations on suitable characterization techniques. We also discuss in detail the utilization of these ultrathin 2D nanomaterials for wide ranges of potential applications among the electronics/optoelectronics, electrocat...

3,628 citations

Journal ArticleDOI
16 Mar 2012-Science
TL;DR: It is shown that graphite oxide sheets can be converted by infrared laser irradiation into porous graphene sheets that are flexible, robust, and highly conductive, and hold promise for high-power, flexible electronics.
Abstract: Although electrochemical capacitors (ECs), also known as supercapacitors or ultracapacitors, charge and discharge faster than batteries, they are still limited by low energy densities and slow rate capabilities. We used a standard LightScribe DVD optical drive to do the direct laser reduction of graphite oxide films to graphene. The produced films are mechanically robust, show high electrical conductivity (1738 siemens per meter) and specific surface area (1520 square meters per gram), and can thus be used directly as EC electrodes without the need for binders or current collectors, as is the case for conventional ECs. Devices made with these electrodes exhibit ultrahigh energy density values in different electrolytes while maintaining the high power density and excellent cycle stability of ECs. Moreover, these ECs maintain excellent electrochemical attributes under high mechanical stress and thus hold promise for high-power, flexible electronics.

3,603 citations

References
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Journal ArticleDOI
TL;DR: In this article, a coin cell assembled with microporous activated carbon and N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR14TFSI) ionic liquid as the electrolyte was cycled for 40,000 cycles without any change of cell resistance.

574 citations

Journal ArticleDOI
TL;DR: A heuristic theoretical model that takes pore curvature into account as a replacement for the EDLC model, which is based on a traditional parallel-plate capacitor, is proposed and may lend support for the systematic optimization of the properties of carbon supercapacitors through experiments.
Abstract: Supercapacitors, commonly called electric double-layer capacitors (EDLCs), are emerging as a novel type of energy-storage device with the potential to substitute batteries in applications that require high power densities. In response to the latest experimental breakthrough in nanoporous carbon supercapacitors, we propose a heuristic theoretical model that takes pore curvature into account as a replacement for the EDLC model, which is based on a traditional parallel-plate capacitor. When the pore size is in the mesopore regime (2-50 nm), counterions enter mesoporous carbon materials and approach the pore wall to form an electric double-cylinder capacitor (EDCC); in the micropore regime ( 50 nm) at which pores are large enough so that pore curvature is no longer significant, the EDCC model can be reduced naturally to the EDLC model. We present density functional theory calculations and detailed analyses of available experimental data in various pore regimes, which show the significant effects of pore curvature on the supercapacitor properties of nanoporous carbon materials. It is shown that the EDCC/EWCC model is universal for carbon supercapacitors with diverse carbon materials, including activated carbon materials, template carbon materials, and novel carbide-derived carbon materials, and with diverse electrolytes, including organic electrolytes, such as tetraethylammonium tetrafluoroborate (TEABF(4)) and tetraethylammonium methylsulfonate (TEAMS) in acetonitrile, aqueous H(2)SO(4) and KOH electrolytes, and even an ionic liquid electrolyte, such as 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMI-TFSI). The EDCC/EWCC model allows the supercapacitor properties to be correlated with pore size, specific surface area, Debye length, electrolyte concentration and dielectric constant, and solute ion size It may lend support for the systematic optimization of the properties of carbon supercapacitors through experiments. On the basis of the insight obtained from the new model, we also discuss the effects of the kinetic solvation/desolvation process, multimodal (versus unimodal) pore size distribution, and exohedral (versus endohedral) capacitors on the electrochemical properties of supercapacitors.

551 citations

Journal ArticleDOI
TL;DR: In contrast, people today are much less familiar with capacitor technologies, although capacitors also store energy as discussed by the authors, and therefore capacitors can be used to store energy as well as battery power.
Abstract: People today are very familiar with different battery technologies, from small zinc-air button cells to AAA alkali cells to spiral wound lithium ion laptop batteries to fifty-pound lead acid batteries found in automobiles. This situation has come about because people rely heavily on battery power. Common battery applications include, for instance, power for cell phones, Sony Walkman, PDAs, laptop computers, Ipod players, digital cameras, and on and on. In sharp contrast, people today are much less familiar with capacitor technologies, although capacitors also store energy.

538 citations

Journal ArticleDOI
TL;DR: In this paper, high-surface-area carbons were prepared by carbonization of cotton cloth at elevated temperatures (up to 1050°C), followed by activation at 900°C by oxidation with CO 2 during different time periods.
Abstract: We characterized activated carbon electrodes for electrical double-layer capacitor (EDLC) systems. High-surface-area carbons were prepared by carbonization of cotton cloth at elevated temperatures (up to 1050°C), followed by activation at 900°C by oxidation with CO 2 during different time periods. Specific surface areas and characteristic pore sizes obtained from gas adsorption isotherms were correlated with those obtained from ion electroadsorption at the electrical double layer. Electrolytes studied included aqueous LiCI, NaCI, and KCl solutions and nonaqueous propylene carbonate solutions with LiBF 4 and (C 2 H 5 ) 4 NBF 4 salts. We found clear evidence that the porous carbons thus formed exhibit ion sieving properties, and that increasing activation time systematically increases the average pore sizes of these carbons. The electric double layer (EDL) capacity of these samples (calculated from voltammetric measurements) depends strongly on the adsorption interaction of the ions in the pores, and hence the relationship between the average pore size and the effective ion size determines the specific EDL capacitance of these samples. The following order of dimension of adsorbed species was found, based on the ion sieving of the various synthesized carbons of different average pore size N 2 ; Na + (aq); Cl - (3.6 A) < BF 4 - < TEA + (PC) < Li + (PC).

525 citations

Journal ArticleDOI
TL;DR: In this article, a novel microporous templated carbon material doped with nitrogen is synthesized by using a two-step nanocasting process using acrylonitrile and propylene as precursors, and Na-Y zeolite as a scaffold.
Abstract: A novel microporous templated carbon material doped with nitrogen is synthesized by using a two-step nanocasting process using acrylonitrile (AN) and propylene as precursors, and Na-Y zeolite as a scaffold. Liquid-phase impregnation and in situ polymerization of the nitrogenated precursor inside the nanochannels of the inorganic scaffold, followed by gas-phase impregnation with propylene, enables pore-size control and functionality tuning of the resulting carbon material. The material thereby obtained has a narrow pore-size distribution (PSD), within the micropore range, and a large amount of heteroatoms (i.e., oxygen and nitrogen). In addition, the carbon material inherits the ordered structure of the inorganic host. Such features simultaneously present in the carbon result in it being ideal for use as an electrode in a supercapacitor. Although presenting a moderately developed specific surface area (S BET =1680 m 2 g -1 ), the templated carbon material displays a large gravimetric capacitance (340 F g -1 ) in aqueous media because of the combined electrochemical activity of the heteroatoms and the accessible porosity. This material can operate at 1.2 V in an aqueous medium with good cycleability-beyond 10000 cycles-and is extremely promising for use in the development of high-energy-density supercapacitors.

488 citations